1. Field of the Invention
The invention relates to an electronic circuit for automatic test equipment for testing a device under test.
2. Discussion of the Background Art
Automatic test equipment is generally known and widely used for testing a variety of different electronic devices. The test equipment comprises a so-called pin-electronic circuit for generating input signals to the device under test. This circuit also has to represent a correct termination for the device under test and, finally, must be capable to analyze the response signals from the device under test.
As a first possibility, the device under test may have one physical signal line for any one of the logical signals. This case is called single-ended. In this case, the pin-electronic circuit may be terminated e.g. via a resistor to a programmable voltage.
As a second possibility, the device under test has differential output signals, i.e. two lines per signal. In this case, the pin-electronic circuit may be terminated with one resistor at each line of the differential signal wherein the two resistors of the two lines are programmed to the same voltage. This is called a differential signal operation with single-ended termination. As well, the pin-electronic circuit may be terminated with one resistor between both lines of the differential signal. This is called a differential signal operation with differential termination.
Due to these different possibilities, different pin-electronic circuits and therefore different automatic test equipments are necessary for testing the different devices under test. This results in increased efforts and costs.
The invention provides improved automatic test equipment, which requires less efforts and costs by utilizing an electronic circuit for the automatic test equipment according to claim 1.
The invention provides the advantage that one and the same circuit may be used for an independent single-ended termination of any of the lines of the device under test, for a differential signal operation with single-ended termination and for a differential signal operation with differential termination. As a result, one and the same circuit may be used for different devices under test. Or in other words: It is not necessary anymore to provide different circuits for these different devices under test. The effort and the costs in connection with the automatic test equipment are therefore reduced.
In an embodiment of the invention according to claim 2, a diode bridge is used to switch between the different modes of the electronic circuit according to the invention. This diode bridge has the advantage that the automatic test equipment may be implemented for high-frequency applications because it can be made on one semiconductor chip, which minimizes physical distances.
Further embodiments of the invention are provided in the other dependent claims.